Civil Engineering Reference
In-Depth Information
Design of Spiral
A
c
(
)(15)
2
4
177 in.
2
A
g
A
c
c
f
y
f
255
177
4
60
Minimum
s
(0.45)
1
(0.45)
1
0.0132
Assume a #3 spiral.
4
a
s
(
D
c
d
b
)
sD
c
s
0.0132
(4)(0.11)(15
0.375)
(
s
)(15)
2
s
2.17
say 2
(Checked with Appendix Table A.14.)
9.10 SI EXAMPLE
EXAMPLE 9.3
c
Design an axially loaded short square tied column for
P
u
2600 kN if
f
28 MPa and
f
y
350
MPa. Initially assume
0.02.
SOLUTION
Selecting Column Dimensions
c
(
A
g
A
st
)
f
y
A
st
]
(ACI Equation 10-2)
P
n
0.80[0.85
f
2600
10
3
(0.65)(0.80)[(0.85)(28)(
A
g
0.02
A
g
)
(350)(0.02
A
g
)]
A
g
164 886 mm
2
Use 400 mm
400 mm (
A
g
160 000 mm
2
)
Selecting Longitudinal Bars
2600
10
3
(0.65)(0.80)[(0.85)(28)(160 000
A
st
)
350
A
st
]
A
st
3654 mm
2
Use 6 #2 (3870 mm
2
)
Design of Ties (Assuming #10 SI ties)
(a)
16
28.7
459.2 mm
(b)
48
9.5
456 mm
(c)
Least col. dim.
400 mm
k
Use #10 ties @ 400 mm
Check Code requirements as in Example 9.1. A sketch of the column cross section is shown in
Figure 9.7.
